Time Series Structure Discovery via Probabilistic Program Synthesis
This work addresses the need for more extensible and robust techniques for time series structure discovery, though it is incremental as it builds on existing ABCD methods.
The paper tackles the problem of discovering structure from time series data by extending Automatic Bayesian Covariance Discovery (ABCD) through probabilistic program synthesis, resulting in improved accuracy over baselines in interpolation and extrapolation on real-world econometric data.
There is a widespread need for techniques that can discover structure from time series data. Recently introduced techniques such as Automatic Bayesian Covariance Discovery (ABCD) provide a way to find structure within a single time series by searching through a space of covariance kernels that is generated using a simple grammar. While ABCD can identify a broad class of temporal patterns, it is difficult to extend and can be brittle in practice. This paper shows how to extend ABCD by formulating it in terms of probabilistic program synthesis. The key technical ideas are to (i) represent models using abstract syntax trees for a domain-specific probabilistic language, and (ii) represent the time series model prior, likelihood, and search strategy using probabilistic programs in a sufficiently expressive language. The final probabilistic program is written in under 70 lines of probabilistic code in Venture. The paper demonstrates an application to time series clustering that involves a non-parametric extension to ABCD, experiments for interpolation and extrapolation on real-world econometric data, and improvements in accuracy over both non-parametric and standard regression baselines.